Unit Test — Cumulative exam Answers

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1
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How are the current and resistance related when the voltage of a circuit is constant?

A
The current doubles when the resistance doubles because they are directly proportional.
B
The current doubles when the resistance doubles because they are inversely proportional.
C
The current is cut in half when the resistance doubles because they are directly proportional.
D
The current is cut in half when the resistance doubles because they are inversely proportional.
2
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Nina is working with electricity and shortens the wires through which the current is flowing. What is Nina most likely trying to accomplish?

A
convert electric energy to heat
B
convert electric energy to light
C
increase resistance
D
decrease resistance
3

How does increasing the distance between charged objects affect the electric force between them?

A
The electric force increases because the distance has an indirect relationship to the force.
B
The electric force increases because the distance has a direct relationship to the force.
C
The electric force decreases because the distance has an indirect relationship to the force.
D
The electric force decreases because the distance has a direct relationship to the force.
5

Georgia moves an unattached piece of wire back and forth over a magnet. Which best explains what will happen?

A
A current will be induced because the wire moves through a magnetic field.
B
A current will not be induced because the wire moves through a magnetic field.
C
A current will be induced because the wire is not part of a closed circuit.
D
A current will not be induced because the wire is not part of a closed circuit.
6

Cora, an electrician, wraps a copper wire with a thick plastic coating. What is she most likely trying to do?

A
keep the electric potential of the wire balanced
B
decrease the wire’s resistance
C
increase the voltage produced by the wire
D
keep a current from passing out of the wire
8

Which will a positively charged object attract?

A
an object that has a negative charge
B
an object that has a smaller positive charge
C
an object that has no charge
D
an object that has a larger positive charge
9

Which statement correctly describes Earth’s magnetic field?

A
A compass can lead a hiker to the geographic North Pole.
B
The magnetic pole near the South Pole is a north pole.
C
Compasses point toward a magnetic pole that is a north pole.
D
Field lines circle Earth from east to west.
11

What is an advantage of series circuits?

A
Adding more batteries will increase the current.
B
There is more than one path for charges to flow.
C
If one bulb goes out, the other bulbs still shine.
D
Light bulbs get dimmer as more bulbs are added.
12

Which device manages the flow of current in an electric circuit?

A
the wire
B
the switch
C
the battery
D
the light bulb
13

In a movie, a character cuts a wire, which stops the countdown timer of a bomb. What does cutting the wire do to the circuit?

A
It opens the circuit so that electric charges do not flow to the timer.
B
It closes the circuit so that electric charges do not flow to the timer.
C
It opens the circuit so that electric charges flow to the timer.
D
It closes the circuit so that electric charges flow to the timer.
14

A bar magnet is cut in half, as shown. Which shows the pieces after the magnet is cut?

Question illustration
A
2 pieces of broken magnet with a jagged edge on the inside side of each piece. On the left a piece labeled N S from left and on the right a piece labeled N S from left.
B
2 pieces of broken magnet with a jagged edge on the inside side of each piece. On the left a piece labeled N S from left and on the right a piece labeled S N from left.
C
2 pieces of broken magnet with a jagged edge on the inside side of each piece. On the left a piece labeled N and on the right a piece labeled S.
D
2 pieces of broken magnet with a jagged edge on the inside side of each piece. On the left a piece labeled S and on the right a piece labeled N.
15

What is required for an electric charge to flow through a wire?

A
zero resistance in the wire
B
a balance of electric potential
C
high resistance in the wire
D
a difference in electric potential
17

Tisa makes a diagram to organize her notes about charging objects.

Question illustration
A
Electrons move between objects.
B
The objects do not touch.
C
The objects develop opposite charges.
D
The objects have the same charge.
20

How are the magnetic field lines near the south pole of a magnet affected when a second south pole is brought near it?

A
The field lines combine with the lines around the second south pole.
B
The field lines overlap with the lines from the second south pole.
C
The field lines bend toward the second south pole.
D
The field lines bend away from the second south pole.
22

The diagram shows a coiled wire that carries an electrical current.

Question illustration
A
the magnetic field
B
thermal energy
C
light energy
D
the electric field

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